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[flybobby]

Anyone give any advice on this?;

I have a 12v 7ah SLA which I purchased with a mains charger.  I have used this battery on several occasions, and it usually recahrges within a few hours.
The charger is if the automatic type, where a red LED shows charging, and then goes to a flashing red LED to show trickle charge.

After its latest use (it was not fully charged) I ran it until it was almost flat! (having too much fun in the river ) and now it doesn't seem to want to recharge! :-\  It has been on charge for around 15 hours and has not yet gone onto the flashing LED stage!!

Have I forced a deep discharge of the battery where it will never recover?
Is there any way  I can test the state of charge with a multi-meter?

Thanks all for you advice

[barriew]

A multi-meter will give you an idea of the state of charge - if its not over 12 volts it probably isn't charging. (Disconnect the charger before testing ) You could also check the voltage output from the charger just to make sure that isn't the problem.

Barrie

[ministeve]

you do not say how old the batt is but these batts can take 18 to 20 hours to charge after a big discharge. if bat still wont go to trickle then try a local alarm fitter they should carry a test meter that tests the batt for ampage(capacity) held. alternatively you could try chargeing it for a short time with a higher rate charger

[Shipmate60]

a 7Ah shouldnt charge less than 15 hrs from fully discharged, no not zero volts.
These batteries should be charged with a constant current charger or the plates will distort.
SLA batteries are not good at dissipating heat, or excess gas so should ALWAYS be charged on constant current.
This is why fire alarms etc can permanently trickle charge.

Bob

[cbr900]

I have a few SLA type batteries in 12 volt and 6 volt, I have only ever used my quick setable charge rate charger with out a problem, all are well over two years old, I think the problem of over charging these types of batteries only seems to arise normally when the charger pumps in to much to quick, I try to never charge any higher than 1.5 amps and most batteries charge up in only about two hours at most,.....
So check the charge rate of your charger and then test the power capacity of the battery, and you will find an answer with one or the other, of course unless as someone else said it was not yet fully charged in the first place.......



Roy

[flybobby]

Thanks for all the help folks, the good news is that after around 20hrs charging, she went into trickle charge All is well :)

[James@mp]

Just to add my tupence worth,
Becareful at using your current charger with the little red led on to charge a nearly flat 12v sla. The reason for this is the charger will try to bring the voltage up on that battery and cause the charger to burn itself out. We see this sometimes and the natural assumption is to think the charger is at fault, but if you put a normal volt meter / multi metre to make sure you have at least 12v at the battery terminals. These batteries shouldn't really take longer than 22 hours to charge up when the charge rate was 320ma.

hope you havent had your fun interupted any more by having flat batteries.

[FullLeatherJacket]

I don't know very much about batteries but I was always told that SLAs should be charged at a constant voltage while NiCads and NiMhs ditto at a constant current.
Works for me every time.
Have I been doing something wrong?